In recent years the need for a rapid processing of light-sensitive materials has been increased. With respect to light-sensitive materials utilizing X-rays, in particular, the system of completing the photographic processing in 45 seconds has begun to prevail. In addition, the need for diminution in replenishing amounts of processing solutions has also grown. Under these circumstances, the tendency to reduce the silver coverage has become much more pronounced. However, the reduction in silver coverage causes a decrease in the rate of screened rays of infrared sensors installed in a conveyance system including an auto-developing machine, and thereby it becomes impossible to detect the position a light-sensitive material takes up, which is responsible for defective conveyance.
A method of reforming the poor condition of detection by the use of certain infrared absorbing dyes is disclosed in JP-A-62-299959 (The term "JP-A" as used herein means an "unexamined published Japanese patent application"). In using such dyes, however, it is necessary to make the dyes adsorb to silver halide grains, which imposes a load on processing steps (especially on the fixing step) and complicates the handling upon coating. Moreover, those dyes themselves absorb light in the visible region, and this absorption comes into question with respect to black-and-white light-sensitive materials which afford a silver image as the object of observation. On the other hand, JP-A-63-131135 discloses another method for improving the defective detection, in which light scattering grains such as silver halide grains are utilized. The screening effect of such grains upon an infrared sensor is small because this method takes advantage of their refractive index alone and, disadvantageously in the case of silver halide grains, a processing load is imposed on a fixer. Therefore, the situation becomes very serious in the case where replenishers are decreased in quantity and a rapid processing is carried out.